Apparatus for artificial oxygenation of blood



Dec. 25, 1962 J. J. WILD E'TAL 3,070,092

APPARATUS FOR ARTIFICIAL OXYGENATION OF BLOOD Filed Dec. 4. 1957 2 Sheets-Sheet 1 ENVENTOR$ Jul/1v AZ Wmw BY H W HH/PAGL 3,070,092 APPARATUS FOR ARTIFICIAL OXYGENATION OF BLOOD Filed Dec. 4, 1957 Dec. 25, 1962 J. J. WILD ETAL 2 Sheets-Sheet 2 INVENTOR) Jbmv J. Wu. BY M M #EUPE't flrromvsys United States Patent Ofifice 3,070,092 Patented Dec. 25, 1962 3,070,092 APPARATUS FOR ARTlFlCiAL OXYGENATION OF BLOOD .lohn Julian Wild, 829 th Ave. SlL, Minneapolis, Minn, and H. W. Heupel, Christophstrasse 79, Dusseldorf, Germany Filed Dec. 4, 1957, Ser. No. 700,657 4 Ciaiins. ((11. 12 3-4214) This invention relates to the artificial oxygenation of blood, a medical practice carried on primarily during cardiac surgery.

As early as 1882, physiologists were able to oxygenate blood artificially. The development of thoracic surgery and controlable coagulation, combined with recent availability of a wide choice of synthetic materials, have stimulated surgical attempts at open cardiac procedures with artificial extracorporeal circulation, bypassing the heart and lungs. The development of oxygenators for clinical use has proven to be a difficult problem. This is partially due to the fact that respiratory gas exchange is only one function of the human lung. Another important function is the filtration of emboli to safeguard delicate organs in the systemic circulation.

Three basic successful principles of oxygenation have emerged from past efforts. They are (1) membrane diffusion oxygenation; (2) bubble oxygenation; and (3) film oxygenation. The present invention is concerned with film oxygenation, as it is felt that this principle can more safely and more practically be adapted to use in surgical technique.

Film oxygenators are characterized by exposing a continuous thin film of blood to an oxygen atmosphere. Physical and chemical properties of the filming surfaces with respect to blood are of utmost importance and must be considered in design in order to minimize blood damage. Since blood is a very delicate tissue when removed from the body and exposed to surfaces and atmospheres foreign to it, the handling of such blood becomes of vital importance to the surgeon using extracorporeal circulation apparatus. This is particularly true where the operative procedure requires lengthy use of the artificial heart lung machine which is the combination of an artificial heart with artificial lungs. Post operative deaths, where such machines have been used, are attributed in part to subtle blood damage caused by prolonged mechanical handling of the blood.

Various chemically inert surfaces have been used for film oxygenation of blood. However, inasmuch as such surfaces are non-wettable it has been difficult to maintain a thin film of blood thereon. Other surfaces formed by a woven mesh of silk, nylon or stainless steel have been used but are not completely satisfactory for various reasons.

From a theoretical viewpoint, blood plasma is believed to provide the best filming surface for blood. In practice attempts have been made to provide such a surface by filming blood over blood foam or by the absorption of protein onto plastic surfaces. One of the basic purposes of the present invention is to provide a means for forming a plasma filming surface for the filming of blood.

A primary object of the invention is to provide a method and device for the film oxygenation of blood which provides for extremely rapid oxygenation as compared to heretofore known filming processes.

Another object of the invention is to provide a blood filming surface which will distribute blood over an extremely large surface area in a very thin film to expedite gaseous exchange during the oxygenation process.

Another important object is to provide an apparatus for film oxygenation of blood which allows the atmosphere to which the film is exposed to be controlled in respect to the composition of gases, water vapor content, gas tension and the like.

Still another object of the invention is to provide an apparatus and method for blood oxygenation which provides a filtering action to remove clotted blood, foreign debris, air bubbles and the like.

With these and still additional objects in view the invention broadly comprises the method of oxygenating blood by filming the blood through a highly porous sponge material which has been pre-saturated with plasma and simultaneously passing oxygen through the material. The invention here concerned also includes the filming surface itself and an apparatus for carrying out the process. This apparatu generally comprises a battery of thin leaves of sponge material alternately separated by separators with the battery mounted within a sealed container so that the sponge leaves are supported vertically. The container has blood inlet and outlet connections and oxygen inlet and outlet connections for passing blood and oxygen simultaneously through the sponge leaves.

The above mentioned and still additional objects of the invention will be brought to light during the course of the following specification, reference being made to the accompanying drawings, in which- FIG. 1 is an exploded view of the apparatus for carrying out the blood oxygenation process.

FIG. 2 is a side elevation of the oxygenator in assembled operating condition and with a side wall of the tank partially broken away to show the blood filming battery.

FIG. 3 is a section taken along line 33 of FIG. 2.

Referring now more particularly to the drawings reference characters will be used to denote like parts and structural features in describing the oxygenator and the oxygenation process. The numeral 10 designates generally a tank having a top opening 11. Tank 10 is preferably formed of transparent plastic such as polystyrene for observation of the interior elements of the apparatus and the blood as it passes therethrough during the process. One side Wall of the tank is provided with a plurality of apertures 12 spaced longitudinally therealong. These openings are for admission of oxygen to the tank. The opposing wall of the tank is provided with an oxygen out let port 14- which is encircled by a nipple 15 for attachment of a carry otf tube 16. One end wall of the tank is provided near its bottom with a blood outlet port designated at 17 for draining blood from the tank bottom.

An oxygen intake manifold designated at 18 is mounted on the side of the tank so as to cover all of the apertures 12. An oxygen supply line 19 is connected to the manifold to supply oxygen to the interior thereof. The inside of the manifold is preferably filled with a filtering mate rial such as the sponge 20. This filters the oxygen as it passes into the tank 10 and also assists in diffusing the oxygen to equalize distribution to the tank inlet apertures 12.

The blood filming battery sets Within the tank in and is designated generally by the number 21. it is inserted into the tank through the top opening 11. The battery comprises a plurality of rectangular plates or leaves 22 of sponge material which are separated from each other by rectangular grids of wax 24 which are alternately assembled with the sponge leaves. The upper and lower sides 25 of the separator frames 24 have an enlarged thickness enabling the leaves 22 to be held in clamped condition between next adjacent separators While yet being spaced from the longer vertical sides 26 of the frames. The leaves 22 are thus lightly clamped only at the top and bottom. To assure separation of the central portions of next adjacent leaves 22, each separator frame 24 is wound with nylon thread 27 the windings thereon being vertically spaced. The battery may be bound together as a unit by connecting the ends of separator flange portions which are in fact the corners of the frames as by melted wax.

A blood intake manifold for admission of blood to the oxygenator is designated generally by the number 28. This comprises an inverted tray shaped member 29 adapted to fit snugly over and around the top of the battery 21 leaving an enclosed chamber 3t} over the top surface of the battery. The downwardly turned side wall 31 of the member 2? is peripherally sealed to the battery as by Wax to prohibit liquid flow from the chamber down along the sides of the battery. A peripheral flange 32 is provided around the exterior of the manifold to rest against the top wall of the container 1! so that the battery 21 is held in suspended condition within the container and spaced slightly away from the bottom thereof. In assembling the apparatus flange 32 is sealed to the top of the container. A header 34 has a plurality of inlet connections 35 leading through the member 29 and in open communication ith the chamber 30.

Operation of the isclosed apparatus in carrying out our improved process of oxygenation will now be understood. Line 19 is connected to a source of oxygen under pressure so that oxygen is constantly passing through the manifold 18, filter 20, and apertures 12 into the tank 10 and out through the port 14. As oxygen is passed transversely through the tank it will obviously fiow between the frame portions 26 of the separators and through the porous sponge elements 22.

The header 34 is connected to the supply of blood B to be oxygenated. As the blood passes through the connectors 35 and into the compartment 30 it is distributed over the top of the battery. From compartment 30 the blood soaks down through the sponge leaves 22 held between the separators 24. The blood films down the sponge leaves and runs smoothly into the bottom of the tank and out through port 17.

Thus as the blood gravitationally passes vertically through the battery and the leaves 22 the oxygen will pass horizontally therethrough and edgewise through the leaves and the spaces between the leaves past the blood filmed thereon.

The material used for leaves 22 is an inert, hydrophilic, absorbent material with an open pore sponge structure. Of the sponge materials available we have found that a polyvinyl formal sponge sold in the United States under the trademark Ivalon by The Simoniz Company, Chicago, Illinois, is most satisfactory. It is felt that Ivalon sponge best approaches the human lung in operation, since in addition to superior filming qualities, a filtering action can be obtained. Since a sponge has myriads of pores of many different sizes, the blood, in constant mild agitation during the filming process, flows over a much larger surface than would be so over a flat sheet of the same size having a smooth surface. With the blood flow at an optimal level erythrocytes run over a plasma-wetted surface in a very thin film, always exposed to some oxygen, thus simulating a capillary flow. It is found that sponge material such as Ivalon has the definite advantage over other known filming surfaces of maintaining a blood film even with the lowest possible flows. Film breakage over unsuitable surfaces at levels thick enough to cause incomplete oxygenation is well known. fvalon sponge can be saturated with nearly its own weight of plasma as a preliminary procedure, and thus present a blood-like surface to the blood which films over it.

The Ivalon commercial sponge was tested for various characteristics prior to incorporation in the oxygenator. In order to test the absorptive capacity of the material, a piece of absolutely dry sponge was weighed and placed in a pool of freshly drawn, heparinized blood. After allowing time for maximal absorption, excess blood was allowed to drip off and the piece was weighed again. It was found that the sponge had absorbed 9.7 times its Weight. The piece of sponge was then squeezed thoroughly until no blood could be seen on a blotter and once more was weighed. It was found that the sponge still retained 0.63 times its original weight.

Next, it was necessary to determine the nature of the absorbed liquid. The piece of sponge was washed in a large amount of normal saline and the total protein content of the resulting solution was determined chemically to be 0.28 milligram. The total protein content of plasma separated from a specimen of the blood used was found to be 0.27 milligram for a volume substantially equal to that absorbed by the piece of sponge. It was concluded that the liquid absorbed by the sponge matrix was plasma.

An experiment was conducted to test the effect of the sponge on streaming whole blood. A slice of Ivalon 10 x l x 0.1 centimeters in size was saturated with freshly let, heparinized blood and was suspended in a measuring cylinder. Venous blood was obtained from a subject by a hollow needle inserted into the arm vein. This blood was dripped onto the top of the sponge strip from the needle for sixteen minutes. The blood flowed down the strip and dropped into the bottom of the cylinder. Three drops of Heparin solution were added to the strip during the experiment to prevent clotting. The shed blood amounted to cubic centimeters. The blood soaked strip of sponge was then immersed in a formalin fixative. Frozen sections were cut from the top and the bottom of the slice, transferred dry, and examined microscopically after thawing. Free flowing erythrocytes with no evi dence of clot formation were seen on the surface of the sponge. A preparation was made and stained with Wrights stain, and again no evidence of clot formation could be found.

With these experiments having proven successful an oxygenating apparatus was built in the form of that shown in the drawings and hereinbefore described.

Several experiments were made testing the oxygenator disclosed using Ivalon commercial grade polyvinyl formal sponge. In each experiment matched, outdated, citrated blood was used with a container thereof suspended above the oxygenator. The primary volume of the equipment was 50 to cubic centimeters. Oxygen from a storage tank was blown directly into the oxygen intake manifold 18 at a rate of fifteen liters per minute.

In the first experiment blood was allowed to flow into the oxygenator through line 34 at a flow rate of 900 cubic centimeters per minute. The blood being discharged at outlet 17 was found to be considerably redder in color than the entering blood. However, examination of the sponge leaves showed them to be overloaded with blood, reducing the effective surface.

In the second experiment blood was allowed to flow into the oxygenator at a steady rate of 250 cubic centimeters per minute in an oxygen atmosphere. As the blood discharged from the tank it was a bright red color.

In the third experiment showed a blood flow of 430 cubic centimeters per minute was the approximate upper limit for effective oxygenation with this particular experimental unit. At this flow rate the sponge structure could still be discerned, indicating that the filming surfaces were not overloaded and a striking color change from the tops to the bottoms of the leaves was noted.

A sample of reduced blood obtained from the reservoir directly prior to the third experiment was found to have an oxygen capacity of 15.12 volumes percent, with an oxygen content of 6.42 volumes percent, or 42.42 percent saturation. After running through the instrument at a flow rate of 430 cubic centimeters per minute, the blood sample had an oxygen content of 14.28 volumes percent or 94.44 percent saturation.

The apparatus disclosed is not only an extremely effective oxygenator but has the additional advantage of being usable in a closed system where the blood is not exposed to the outside atmosphere. This prevents drying of the blood by conserving water vapor.

The apparatus with its sealed tank or container also allows strict control of the oxygen tension within the tank to accelerate oxygenation where necessary. The device may be incorporated with a closed system anesthesia machine to control the absorption of carbon dioxide.

We have thus provided a new and improved filming surface, apparatus, and method for efiectively carrying out the aforementioned objectives. It is understood that suitable modifications may be made in the structure as disclosed, provided such modifications come within the spirit and scope of the appended claims. Having now therefore fully illustrated and described our invention, what We claim to be new and desire to protect by Letters Patent is:

1. Blood oxygenating apparatus comprising a container including a closed chamber, blood inlet and outlet means on said container communicating with said chamber and defining a predetermined path of travel for blood through said chamber, oxygen inlet and outlet means on said container communicating with said chamber and defining a path of travel for oxygen which intersects that defined by said blood inlet and outlet means, blood transfer and filtering means comprising at least one body of soft, absorbent material including myriads of random spaced and sized pores and capable of pre-saturation with a wetting agent and promoting blood-filming thereover in addition to filtering of the blood with a minimum of mechanical shock to the blood, said material being disposed intermediately of each of the intersecting paths of travel.

2. The structure of claim 1; said blood inlet means being located above said body of material, said blood outlet means being located below said body of material, said oxygen inlet and outlet means being located on opposite sides of said body of material.

3. The structure of claim 2; said blood transfer and filtering means comprising a plurality of thin leaves of said soft absorbent material, a plurality of impervious separator plate elements disposed on opposite sides of each of said thin leaves and forming open passages across opposite sides of said leaves for receiving oxygen thereover.

4. The structure of claim 2; said oxygen inlet means comprising an oxygen inlet manifold at one side of said container, and oxygen-filter means in said inlet manifold.

References Cited in the file of this patent UNITED STATES PATENTS 2,773,000 Masci Dec. 4, 1956 2,792,002 Malmros et al May 14, 1957 2,833,279 Gollan May 6, 1958 OTHER REFERENCES Bencini et al.: Preliminary Studies on the Sponge- Oxygenator, Surgery, vol. 42, No. 2, August 1957, pg. 342 6. (Available in Science Library.)

Modern Plastics, volume 27, No. 8, page 104, April 1950.

The Lancet, pages 711-712, Oct. 1, 1955.

Struthers et al.: Experimental Study, Proceedings of the Staff Meetings of the Mayo Clinic, pages 462-465, Oct. 5, 1955.

Newman et al.: Complete, and Partial Perfusion" Surgery, pages 32-33, volume 38, No. 1, July 1955. (Available in Scientific Library.)

Helmsworth: Artificial Oxygenation, Journal of Thoracic Surgery, volume 24, No. 2, pages 117-119, August 1952. (Copy in Division 55.] 

1. BLOOD OXYGENATING APPARATUS COMPRISING A CONTAINER INCLUDING A CLOSED CHAMBER, BLOOD INLET AND OUTLET MEANS ON SAID CONTAINER COMMUNICATING WITH SAID CHAMBER AND DEFINING A PREDETERMINED PATH OF TRAVEL FOR BLOOD THROUGH SAID CHAMBER, OXYGEN INLET AND OUTLET MEANS ON SAID CONTAINER COMMUNICATING WITH SAID CHAMBER AND DEFINING A PATH OF TRAVEL FOR OXYGEN WHICH INTERSECTS THAT DEFINED BY SAID BLOOD INLET AND OUTLET MEANS, BLOOD TRANSFER AND FILTERING MEANS COMPRISING AT LEAST ONE BODY OF 